1. Field of the Invention
Embodiments of the present invention generally relate computer graphics, and more particularly to providing filter weights for use in filtering texture map data.
2. Description of the Related Art
Conventional graphics processors are exemplified by systems and methods developed to read and filter texture map samples. Conventionally, texture coordinates, such as u, v, and p are represented in a fixed point format and are used to determine indices to access texels within a texture map. The integer portion of the texture coordinates are used to read four texels, a texel quad, and the four texels are filtered based on the fractional portions of the texture coordinates to produce a bilinearly filtered texel corresponding to the texture coordinates.
FIG. 1A illustrates a prior art texel quad, texel quad 100, and a bilinearly filtered texel, bilinearly filtered texel 105. A bilinear filter center 110 corresponds to the texture coordinates. Each of the four texels in texel quad 100 is read and weighted based on the fractional portions of the texture coordinates to produce bilinearly filtered texel 105. FIG. 1B illustrates a prior art bilinear filter kernel, bilinear filter kernel 115, that is used to produce bilinearly filtered texel 105 of FIG. 1A. Biliner filter kernel 115 is symmetric in the horizontal and vertical directions and each texel within texel quad 100 is weighted according to bilinear filter kernel 115, using techniques known to those skilled in the art.
Accordingly, there is a desire for greater flexibility in producing a filtered texel, including a desire to provide explicit texel weights that are not based on the fractional portions of the texture coordinates.